SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83655ad79f936d1c98fbea382e52eef2678ff5720ea73840582237e68c42a223' 
  AND token = 'y1+7OaU6WdLDsAhqnvLPdn3EKQnmec+ezDLU3hUew24=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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