SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dfc1566cd42a9dcbfdd7442d9f3cac103a15f414b6df7ae97f07776a94acb2b7' 
  AND token = 'm6VDt4p3gnJFt0PLfq5D33WytE2NiBhcv65bbopPNgk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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