SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b04f29032481fd9a54cb6fe382e074b850c130575bba78d374bcdbc85f8b9a3' 
  AND token = 'kkwCwDKmRmpHgzjYFH6JTGqVURPGVkYqIv91nyI/+g0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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