SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b671f93156424ed0042f95a50f724461b46b4c4e30915448a0f97f3e9349a31b' 
  AND token = 'j6pveOpx6BTkDJUiIlmKHzQsHgZYSne8wXMNmbs4gBk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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