SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd4abee50d29031f0b6805a38ba220275bf738d53fad98e9044a30dd865c45f75' 
  AND token = 'SG3nhdXf/EVVuJY4AvWruf6v8+ZcaycOSv+U28U3bJo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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