SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dbf73b9dc0ac59106e1048c100545529789f2f82576625b6b2dd2ac69e171bb3' 
  AND token = 'Z6/RzjjZDzBHxEK+9aBSFcN2YhNMg4nPBcVXBoKeBV0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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