SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a3723c036b13ea82243cd1d7f7993932830ebe715ebe330919034dcb81eb76b' 
  AND token = 'zLzbeCAMuPo7xyNyYIPG3tFkmwsSwrW5deGPJoiQulI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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