SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c8ae9461ed9ecefdc2159ad482d8fdca8a21c3eaa8df42f6c75edfbe9716506' 
  AND token = '10eCcs0rEwsKhkcyaWhcdQF8WUy/CbIQbB+rsO09mRI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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