SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6929b32135f61f1b6d5b1020085668fbd2d4cf1635d73d41c91bf6086207044c' 
  AND token = '0AYF+T8T2XlAqcK9PjHBKXUROwKJ18/6cs3OGHt6Yz8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}