SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2ff45dc1d1e41ace6c771cda24cc940bec3ead9497644e4e0ab2b0ea98217442' 
  AND token = 'X7z2zYcVSRcHMLIYn/5TLzVdVjxtk9dgVoOz/88KTj4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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