SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a26437c7e9901f12b846951bde253ef62513ceceeb09ff1ea9bd0d83dfdf95d8' 
  AND token = '/jeHBBGwCDqEuyKihGJXVJIZKvXxB1jYQcAi/srokyg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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