SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff803b0f473d924d1030eac0c8b43aa276a74668d21760a892a13b7fd9f1ca88' 
  AND token = 'P4vFOmUcm6ZuMCEakGgfIBXIJp5HvGr0TrstXSiq6XU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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