SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '89b545b35bc3b44a20e099fa505a3b30bf2a14be6321f082f355cc1ac7b4dc83' 
  AND token = '4tlT8h9y7gSbta2fRzGejcv8fAzl/corMZzCRsCYFqg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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