SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b9d37a39efde57cde1d40ecc08d4255a24051e39e77dc35c709df68bfaae277' 
  AND token = 'MDbezLjfO+JA757FMc4JIr3FvyiotrBwjUvv23JhgfE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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