SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81995de60d68a2361bde84bbd561c805c3835568ec42ec5646f3e60ab6f07cb9' 
  AND token = 'lj8rgqzXT/4O4KCE8xTGBKS3SzwRHZVOn4DUgzZH0ZE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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