SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '258c0ab3ee5139b1a042992078fd689ce406e65c70a1e829987c139d53b1f5b6' 
  AND token = 't5dbYKL/hEQPGfI36s4eiIY/ehJg7ulj+dnQP8mBgx0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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