SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad763b1a16378f4795d8ff9b70eef12e58c70aab0c8719fa715a006187eea96c' 
  AND token = 'x66LnwIOkitw6SJa4JsY57cILhnzcDC9SCQqEDyWcfE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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