SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cca1716ec4d9b5a08cb4337250db1be04e3573483e937dc462a540f22147ea03' 
  AND token = 'Bxp/sPYu+ElzQvI0eG5pV+UA/LLdDWSiwGXBZBtGiCs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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