SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '59d40322477b95de115b71914991b85791afafd99454e06a76384d9f71729980' 
  AND token = '7onFjCcbLh+beRhDur6rMY7pj+pxhf84OZH9SdKBzOg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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