SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bb8db5374a1a0a3a2913e97aa4f57b3888c43a67b02fe47e4534d77b15900173' 
  AND token = 'QJyKfzp9pAdxkamKK/hjnBTBmpUAPOiHGOgXGTz8yCk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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