SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '254b82335ee8cb30e2d38ad6d2265b2f298ce72b75061cf297ead51bb3a93513' 
  AND token = '9irVKiroNRF+QB1VKC3RjPCS3FRvUlDPBwMvJ1iEUxo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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