SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27bb2f6a0e44fc277da459bf8185ddaacacb985124e2125763cc9bde49bf850a' 
  AND token = 'sMJmSBbP3/WBZVLZkpbrHaVLWA8HaIET7vLi/XGxH4k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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