SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a72ffe6603eaf1d62a99e77bde10f20e26a68fdf6774bc1375109ff7b56cc5d4' 
  AND token = 'whPZlTotCYG8JbBkOZsiDbQV07NvHD0lE+H2X4s5tJ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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