SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a8f971aa019f138caf1f91612aa374b0abbc1c4d6838aaedfa12818f03f4a7b' 
  AND token = 'orSnp3rXigb6RjrQyFsZaswLUMQdBbIF+TxnkkxRtjY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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