SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b9c730b8c1821e63bf178eb203707971be3119785a006546749da38ba7f602e' 
  AND token = 'aEgz4ZGJOmzZZhEsG3KKvJh0NPgbV09zuwKBRbtumA8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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