SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '212787c91e7b4976065cd0b914c8fbd0674b529073b0b40a118698481307d56b' 
  AND token = 'Yj50qTj/2IHHxW7lCDk5dhhDJ3qUJxPnPuE27xdQVBk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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