SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2c625e4687af78875a863eedc3ff5bbec5bc1be5dd072f4afd8422c597dd00b3' 
  AND token = '4rXzLwb3+y/WRIkogts5hCOVCH3MHCCUcOaVxvTzk/A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00065

JSON explain

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