SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '834204302ee2781ff99634682bc1adac64cf2fe4f71c6d7a893bfd62dec9f14f' 
  AND token = 'LlJYEnhWi+I4bfgKTutb3BjIssx+3H53gJuZ1RNh8pY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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