SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3fe7f8384f764b1af276686088dbe3496571a565b5c6a64783d1a5c7a76d273' 
  AND token = 'cfS/jMq/K+TVvbICorjJOjSUfP8DUpbeh+QlHluaOMU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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