SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f76330fad1dc2dca672bb63492b072d4d2bf1d89772d725f5860cfc4e555d489' 
  AND token = '1H32h+Lcf3vWICKHhMWFGFIZdpu8zjoHj/sl5Wg1j+Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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