SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b50dba30ee160c3b4bebf76ac9b3e0f452837c66fce54f7977270a5ca08acf3' 
  AND token = 'ZkGxwCNv4FvYWyZiz09UyFtzkGewWOesmCTY+Jr0zr8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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