SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f975e97c0c3274d148ecf35b8ce5749cee9b6c88d47b10d047efca35a1f39fc' 
  AND token = 'zdi1pdNfUJAk+JobeVyIOqZj1mJ4Ig7iH7XGQTFoNX0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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