SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c571cb69a1fea2504171949eb39104c915b7fea9c2c70db47efe1fd5951f47c1' 
  AND token = 'z04YkuJ7ODZ37hxQ9PV4tR2kpbb5ZxqIXMWvT+3hjq4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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