SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e306c1d12b200b93182784d93ce61da3396f78acfeea49614c2aa73078acd7f' 
  AND token = 'kemzo5UJFAF5ZOAnJtyluGDh+9HtuVFd/DXcWcV5iTo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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