SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd981b158bc0412dd294638a7b2612a5856909d94ad365855e79e34e207039aea' 
  AND token = '7/Oviu3Z5MBkuCDsuOb4+kgrbczdWuFEPCdwbISM7LI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}