SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '917fd8bc3f55f73951b4c5a085410222a9545054a11c4cdbde46a69f5e790338' 
  AND token = 'ZetwBGzJ26mgo4JxriNEzp7lG55K2tuYgibhJoXwiEg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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