SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c4be800258b07a163f5cd460342693e516ef5fb74e0b7330122c0eb7a4b81f4' 
  AND token = 'YEJnQoXj+YzDHnfJwfM8iaantBd8ajF2CSo07wNnleE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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