SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '550738cc5710fc2b25f8def3335b8786ef6295f91d44d9fdc3ecbf11fbe84070' 
  AND token = 'BNQLsoCE3aq9jKHs+AXgmYiXl5TUQn9qI+AkY9uvoS8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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