SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd8dc09cd3778d0b2e01d3caf89ea569dbad8bd346bb4458a51b8a87412ba258' 
  AND token = '6BScNrhcasGyPp72UUZKJLMB287+cEgZTR8hYrZVYMw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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