SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6d0c6edf61e9d9a5192738715391308ff84a4d066aa1407662ef9ff54a20b63' 
  AND token = 't+xQjawCXXJIyb+7cLX3LsYYCuuIiL7KEGx7/UvDCio=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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