SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a54f1ed1556a7c3fd5736423e6d2ea7653d07e31223a8888e0c24f0c294293d6' 
  AND token = 'HJtDaDid/F4zOJTgy2xFe2rHkd+TjcjtAx6PDilzOfs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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