SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e4a0436ea6dc5a359ae1ff36e21e0b618492b7295d434f1be7d2d3015ffb3c47' 
  AND token = '3ToU8gm/kPPPDwRnVHmK93nvZ/dfqx7VaplZcCDZJ0s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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