SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a55ea14abbe3b49e728466f6542110fded81f876e796efba12a7f6a199aa1164' 
  AND token = 'wKVqZJTRSvTnzZnbtYZtGtyqI6fy9UOR8pd43HFCbpI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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