Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_1555308_1 (prothrombin_time VARCHAR, platelet_count VARCHAR)

### Question ###
How many entries for prothrombin time are there where platelet count is "decreased or unaffected"?

### Accurate SQL ###

SELECT COUNT(prothrombin_time) FROM table_1555308_1 WHERE platelet_count = "Decreased or unaffected"