SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd96676df89d0239ed2358e77465e1d9f81985df013b8b0da139779d473bbdda8' 
  AND token = '1GXvevR9Z6PAOLKjba4haJwq5hzWhWYm+eisIEUrkMI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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