SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bc211e0722ae395f3a8eecde1435d7dfe6202529466a28028ab7706c4729525' 
  AND token = 'GXhY02zePKa+Dfi0NDSVEu5FqPqtDJ8Lg4/LzNQtL9s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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