SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8898409ea8ba13c681922df9136713f09c30726e9370d0d37296fd2baf55cf36' 
  AND token = '+18XSp64HpTMtPFij7qj93tHH8qYGfWrKstjivSX1FQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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