SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '25e0d5fd8519981e1be930922a58e5748f3c28152ca664184afec33e720d2350' 
  AND token = 'QTVJe9fBv5TMbJo2S3lKL/Hb1iqQHMzUguVMWTVsn+k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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