SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38e9eeffb931ec22c6ea667e0518de1fc9100bb3f495b934c36220e295d6bb12' 
  AND token = 'X5hjZWMFtBVvhlEdLAJ1dbqgmuNp7X6CB+O6/ofvRsM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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