SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27cf3c424f760905e77b55f221669f5bb863184af45e10a77d41e52adee84a2b' 
  AND token = 'hbEMeQLN6PoujjKLXUMM9ZZt8DmZKYkTcWCT3Jpwag0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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