SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5950f6ccfa0e6ae4549e5bdd08599fa9480860d180c24a84af6ed8797f99dff2' 
  AND token = 'S3JsZdfdr7s601GhQgOoj06Xqp+4ohMvVsHNQdrT/vA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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