SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bcd6f22d2dca301a681cd818c972a47746a37eebad7f8ddff8e58aa1dddfd61' 
  AND token = '2mdUaV/2LNcSrUi/9wEVqSkV483+YNTWe2AVcRmIi7w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00067

JSON explain

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