SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a15f5531bcdbe2de04fd7a45d0a674455bd98998bd999a3bc710c80d5c58a451' 
  AND token = '8WJ17yfchoTUPZd4k16oFcq3KmP6AhhOXArNPYY94gA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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