SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6daa334e46691326de325decf97df09bab03ee79ba3abdcee1b5c6f2344b6b1b' 
  AND token = '2d07xCb2WJlajmHz0loDP3GcQOEgOPDWIeMfnHM22+0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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