SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68fe0ff9b077c07ed0cb50e32e635af7cb531540e1e247fc11272c8427cfa49d' 
  AND token = 'xxr+jj3KFtVHLqv0MT1JsqCJkIwwIsWVmgWAAUpL5ME=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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