SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd7b4207ccf05107a5f3a86a9184820ccafccd135ed240bfb925ded102808521' 
  AND token = 'nZUk297j5+QPyFJvtV7EI7ibur/GulWGwPSZbVPUE/I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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