SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '14251b7813d143600580a4eeddc300aefb94de9677545c269daa33cacf95eb22' 
  AND token = 'gy5qUxdaZRG6ZBqvYghQ4P6Gkh2dXhhWHDi+KJ/K9BA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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