SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a500c276f27cca667a68c694a50266111d404f03fb13d9b6ccc0b1cac85041d' 
  AND token = 'FhePJghDE+3bdyesVptGs02bqTBAQl1n0i52ZPzC7fA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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