SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6db8a36a4a776f87a5013a8c27f3e26dbff1f8f4dfeef381626b2f34beca28c9' 
  AND token = 'bcUFItajiADPsC6Nfmai6F2MVT7dOeALTW/d3CSvOsw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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