SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e2a4a761f5f8510b57814ec9662672a215051fe0ff96dfea5d9b547aa9ab4826' 
  AND token = 'eSbmlKYd+lSt+xdXIMMxPWH3kI7n9f+/M5cZnOIam40=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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