SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc75ef356445c9f708d978b0bd7bc82037781248e6b7c16076fedd1115cca510' 
  AND token = 'dNiYiRTuClYFCz+7wct/UVD8XGaAEEELqWZ9r4vTVfg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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