SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf8f6923353c61806a84fa47450d961786fc766371a46d7fc83fccf846f3a360' 
  AND token = 'xkTRSZ9pj5wJHRjnuf5IuOQ+TWtx0RagbBuILcRpuFI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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