SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39376487c4843523a49a232694cc21278126d359025f28843eadbc290681cf24' 
  AND token = '3Uj2zUulk7hn1KXUCHAuIB2Kj9eNQ0HapSdnavXEW2g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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