SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8fd926fabe4687effbde71e4a00479cff48f4374921410935067b8e111435c8' 
  AND token = 'qAmPM3o+lfAJE969kG+1XsLCRVlOY5l+vRJgWlwCkK0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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