SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6dd509c25efdc8982003a65551013e69b98d56664b3d1ab3fcee4246b828b4cb' 
  AND token = '4HFxnTJPZtzsFUaM0uCs3UATx0s/q9LGk75LMKdnZgg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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