SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '47923383f80702cf4adff946dbe63170e8d3880931e49fe3d95175227fcfd316' 
  AND token = 'KjU3V/2YUodmkal1r51XjhLWB2NFv+d+egU6oB5f5rc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}