SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8028dc25afef822c1b8a770472b51357a444909784b495b30f940c50e37bd83c' 
  AND token = 'luP0+kshx1KLCQSjCLkQlu14LOj/rblqKFQ5RkrsmEM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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