SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e210c20433fc90bbe48f6193b80ac2a7eb790b847872446472406b2d12f69fba' 
  AND token = 'yVDOE3KH25hmZsOOfLvRfzAznuvH+TgFYe/RpnpXMKU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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