SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4635a4b09262f4e5af842dccefa7aea09d4f3083ece32a83e11b036aa1e1a4e' 
  AND token = 'QrmIQz0rzPLG5j7qi7EEByXdTdnYV+qf/zHBiUwyyWg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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