SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '198c8c5862a45ddb0ef22cac234bde494c734fa37e57b76f50203c7dcf44aec2' 
  AND token = 'g41UUruFCfPfxRe9eqPl8EmOe890L4lWhlSW81l6b8E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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