SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a91710136b011769069eafd7fe0b01907dabb091c4e5611b7179f4daa5017c1' 
  AND token = 'nrMNaCgLTvZohIG2oglJ29y1zWbPmcTibcTn3MrpeCM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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