SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '553d97846d374248bc3c225613e3ef24499b57b7b9d550e6066bae2ff461d233' 
  AND token = 'hfAGHtV7d8HQqo6ktWF7twVLx84YjiptNi+UxesxLuU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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