SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c855e9c1bca8b9b1c4badb1e88a6ba79a12c58222ed6fcf00b2a0f603c5dbac' 
  AND token = 'xV6YP0zJiU5NwuDidjrkzoVdpdPaE6vxqYgdk8/bOAA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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