SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4731ceee1c8f17960c99fabec36afe97c43ead915caed6c4820b746af931d2a5' 
  AND token = 'WWu+M48gbMqblHoSAsEVxeXuAHbBT/GHvLOJ/4xrck4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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