SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f21401dd4d27425624b5919833db6f215391329850d014d12e4315b304c214b' 
  AND token = 'dSiIMUuxuxuTsiDlltDdaY/RaV82Xd2SE8jLqk2nEC8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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