SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '265cb88c4947e9761988bc96d0029595ebef1fa89756d04504987483e46d2bb9' 
  AND token = 'n4IRrNap6w5BpjKgqcd/iVvgcdkNAOxUZxfGDX+EnyA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}