SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '97f32758644a72f3396ec31d24f2937345308d39f587d150d0d1c481a583b3c8' 
  AND token = 'ADvzvFjh8OADy/8Jw8BH2KiIobvzoZWXOVvAM48fMUc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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