SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a3201cdb14001b336a446c2bad9e9341fc8a8554c7398922a4b96ff27184a76' 
  AND token = 'FgZMlsNO+v6p9/8tmjELjdaYYXvz0fu11FUIplTDihE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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