SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38e53d5683e6eef138a753722cce42be9c8b48a1a608f969f6026013a657bca5' 
  AND token = '0hVbwbWMvXuT2g9V1H7fwwwjMPHeHIafbBP8hXYsIq4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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