SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4177cb5a12bbd44227badb204068623a53661cb5c560646790ba2e03e43ab0b' 
  AND token = 'DGX6A8vVv8RkFWCcVZO/ZwIrY/Xz1RD3++1bAwTgGQg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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