SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '770a96efea915ee603086814f3a8b2648e4938e4ca572e719e0b1d6250cb0e03' 
  AND token = 'UIp99VnzwdZVXi8H/WzAVRw+bhJD4KMfK1CnVGLkTfk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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