SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76a2f803cf415420ee5c899ac7b2749c33d2ec527cd2b7f438fb943177955c02' 
  AND token = 'P9JDjtVHZ0W8nmLGQ/tTzlXUadImxkjK9MgXK+IVWSs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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