SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '36c9d15a2d1fba9b98c0bd03f4dc2e338df969d0568fe979f50e205a59147e3a' 
  AND token = 'uNzihViwBtVOrrq5iYFN3K+WDwgLtGKUO4eQv0XPMKI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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