SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8db0f2c28d2f5fff354440725d028a276adf3259a34a8e694359220ac033b20f' 
  AND token = 'oDuPnvFfKCCExpsKppo50DrCZuuU1yz7I6kPmGpRhZs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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