SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '677b763ec7f4867df46f1908dff29818e4e574d5cb37cc4e6bbfa38438d899c1' 
  AND token = 'FgaxdD5ijYSsMnSQqxARa5mH8zf1aVdrKBjxIFmYtf4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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