SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '611a7b798e826fc43f097696696d496c8d4458234f13a85ac20f19aaa58b9e5b' 
  AND token = '/AxoL1i8wDSyJTIniyTHBSYsfcPzKNZBeI1iGZSac9E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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