SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '94d53e6bc914a91ad54ecb226834074edc424c5fef9bb521b541896d8deb5830' 
  AND token = '5FLTmBgJteEMNk01FlYRt1oU81bNHG3Nn7TfgGRvduM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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