SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b35b4ed46196bbb713ffb47f34f5cf283b168d19f3d8e0560e6b5347815c3408' 
  AND token = 'VeLi0F7sgVBVhBOCvqB0jMqQp/BLEjildOuk60EAYtA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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