SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4dceb514b945ae04c3a699fc7f89264d6281f5eaa1130f15c3f11eb058084f91' 
  AND token = '5GzkwEl4ysqPjAvpq5f2OaCTcJetxBV1DxazAAtbtM0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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