SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '267885271dcb5b9f0cd3d3e91fca124469c07bdd69dd77f9b5c4bdd8cf31b0c6' 
  AND token = 'mcuTd77D/cq+bZCoIzLxJ4htYbLY0mwf3E0nbw1gVBc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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