SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b12f221c168eba74697265ccce8d5310dd1653ad45640f542cbdfa4c0f0bcd4' 
  AND token = 'L2aWHEit+t4eRuzGiwzfkKRAToR0NestkR7NSe4PiJI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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