SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20d0028f2baa9bfc8942dee210c03dec36d0fb9aa498e6aab3cebb33492b0c3c' 
  AND token = '9OZKvPOi91/UqwBchelxjqDNEplYHb+6wfExqxcUg5M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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