SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6c2761401b78455db32bca0b4d532489758c198dad53419d58bcea17210bdf9' 
  AND token = 'KqpvOSlGOiDYc1dkXwLH1Jpjr4Qu4yNIHlFakFroLpI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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