SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3055c975e7bff611dbe3578fea21bf5d2b908ca5140dc27d929b0bee78dec860' 
  AND token = '3CkOwk+ewxSfoWbhKDdXhyeQio5see51elbRbkzC9p0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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