SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15de93ecfb63ec994577513f997e6c7a9b19e6ccb3f77dd4ecdd971569c1c170' 
  AND token = '2AnAlpy8fTjUmMR4HmfHmFm83JdvaRwnYLGmZaobZw4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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