SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'ad764f4692377846cec958a2eb9716ec99bf03a38217174c15281ccc76161fbd' 
  AND token = 'zGKlPqS+UaiAW6zqghHB854x44dLXJ5dFb84CI6FgTA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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