SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f453394aca41754c38b0b3febb90460a24c8b7b5d473ba380c7604372d73fdda' 
  AND token = 'LLUV9n9aAW17XTHjEE5qCmOWNG36GOa/71E3dzJHXog=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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