SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ebe1ec3dd94b46f592e8b55fad81118f5d513b7f7dea877ec651779d0bfaef98' 
  AND token = 'nSLQ9YXnS2QNgXJ0JvEuBXosDAL39ewnAdyf5/vUi40=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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