SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '822b8cfa479b147dfa921e74f89f515b287f3f414f934cc5cdaae2028c147e53' 
  AND token = 'XLuqQGjDcjwxzOK/8bKByskmqOEjDg171v+G762yRMI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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