SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20caec3f3b710970330428220245942d213b0de631616ed18ea04a4cbddfb656' 
  AND token = '1JyodlPftbwU/HgLZYpxvjhqnkGhAsihcJ6i20KMMww=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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