SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8eb936ed4bf500916aff5edac87bbde3d6c68555022ee653db868b7ba43a429a' 
  AND token = 'tBaCZEmI99AsddqnbZ0BSvnkiPCl5apuumu8AxY1quo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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