SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4a7e857693e84978c38046e063980782489fc118bcdf5da42c9f5e9a8c95e4e' 
  AND token = '2VS38rx1jxGLpZgN6kDdpWEWmCKwqKfPMPBYQvBwf7Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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