SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7bddf703458defeb292fd0713e40f137afca42d267efec2ae948dcd54a0944ab' 
  AND token = 'aJvOHcirqxxyVnMOby0ApB12Dp8VRznd2fRQvJ3+5U8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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