SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6341ced391574531c0fc833d494380a5cdee763eccf384613ae673c8b38fab3' 
  AND token = 'yvi4dOw8qjgzhe2Raadu2+5rtUv9da/bKV+jLePXNW0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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