SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a165bbdb262c9576d0d76d7c55d92980ee83ff255c271e59942c57e9994cb09c' 
  AND token = 'VKuBwGrJp/D+/X+Doc8NSzX0hGHzifZUqDzy9uI3rG8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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