SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4eff60f890ebf8975ef25f200cb3051ec77b77689b8fe18b147474f7034717b1' 
  AND token = 'iiLfOhnhWZEedtKUd/Nag3mcofJQqKgnsKnkez0knj0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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