SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2f96953649d8152ce1553d2623596bdbf84f4461fe76714389c3374f66ff70da' 
  AND token = '6UqQcXQuTZWHP5ngakek49JwFLYo0CcFW+6wta1Fhiw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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