SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a1be688117d5ea44d92e4f2d393fd6c59b0544ca678c9c39739107559a49329' 
  AND token = 'ERUMuuwZJym4Hj4RggAivXsFVaI/3Wd6lK60jnowOl0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00062

JSON explain

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