SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7fe791dde9b407cc584ffacdf01978a81cd4fc6d1446817eb599655b76b8c40' 
  AND token = 'TE5dOEQaY2LAg3Ezi9q6wNmBQTsdmJKUS57UYEUAW7Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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