SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc278e4dcb6edd24935ada072ff3c3ae5ac8b6fcdde25e52b7b8b28177b9333c' 
  AND token = 'DRuwIRKrwDm7JOA355lX6ggadzXyZFTTeYhp4m0MAqU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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