SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b40b4e153d7e213501ea16bbd40e5a251188c54b496b987de53060f867270574' 
  AND token = '+rFm8x2A7HMWuJ5h5fShh1vCOZI8ZvujKw46OFz6gXg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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