SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0b39bb9f5cb845c7581c3d7493c37e460876667253465714f4ee193073125271' 
  AND token = 'FHG1zF06mGm2y2xmLIRafiluFV2koBlQb8VsYik2/ig=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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