SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b3eb6a80ce109a548f634d5b59503667614afe21ae8f2bad9b44ccd5efc8a90' 
  AND token = 'dytxEFybtM9CoIkNGbCTXukqeoAVhPMnOelmPIfX8vE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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