SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '604786f15fc91991907a55346ddfe697c0fdb656317a6a538b8adaf0ccc9a2aa' 
  AND token = '/sYUKoNrqYiIG/ncHnMXgfReb/x1ArPmeSxTwzu+Q9A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}