SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a42f0b750b27ea9829fc4960236fc63a5e5cb56506097121926e29a306556819' 
  AND token = 'ypj50OsSBKPrpO+vfSUbwLxGqnvOtMbkgCtRZgNuF3o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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