SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '45f803b8c21447a75bcd19109ce29e6531efde120da4d507902841d1d4b97411' 
  AND token = '7oW6GNzSqv2a7YM4ONG8bjlj4MPh+wZuK7ZGNlGPW/s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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