SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e24f4fd03709dff6c37a4c173c6a9e881b375b2f231fdf44a56ca44c9acb9f5a' 
  AND token = 'RKCLfg5NIm3ynczgpAvJv45WvCQP1ofA/uWXJIXALXk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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