SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '88f516d16c9a26425b525f3a43f78b12b81a7bbab471e73d7ddf6bed8243be3a' 
  AND token = 'DFgsvUZ/gC+Vk91zbAjhoCf1P3BPybVVDHIuvLLQwLE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}