SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f159d610675e400f8e4baadb8163d45c0966cf07595fca8aac09b9be047377c5' 
  AND token = '/88W2SD0+XxTwr/pYtXk+lhAmQQW0VWVRuRMuUDaqv8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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