SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c39155273b444c25bd41ddb6cbea1588053e33d5ff34f2813d36242c929231b' 
  AND token = 'UQEjhGEMlKDsDsXVe/1ZHtcCssz/zkgZvdnTlqQBGv4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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