SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c21e58b354af85080887bf963509c898a03db31272f74b13909142e3c8c54bba' 
  AND token = 'YsjbS5U5mIuL6CjVGuICmM/bIXElUkVWZY5shDfyofk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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