SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '608a206012a908787c3d396f894e430561e7693fc9d1dc87330ae8b34a86b619' 
  AND token = 'VMcX7BAzhtw3yYLKeVI4/95dxeQTGPfanw7KdYdOYqQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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