SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4f7e621cf886760ebeba7a9ac8b438d7059c720489632c3a3920d4e58a5e7eca' 
  AND token = 'D4DijqBqJsRZHlvFZHLcW7QsB/AmhmgI0OI7ZlPqgjQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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