SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '750dfdb5ba5bd4afdb58fa26607e6d111ed7822dad24059e1a84112089b815ee' 
  AND token = 'WAD8VprOS+XNDCq9CAF6fygzuvNfRQnVkIN94tunUpw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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