SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af39528e6d495f0925a2be88acb90e889a0f557c74d182e8aa0aab5fcfa2e0e9' 
  AND token = 'WG5LsUi5gY06zPtBDgIaqC0doOmL6dCqmsCmXSUGtP8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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