SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd61ea4297bc58b651831653066a251c23152d3a746273ee57367bf9b10e03c0b' 
  AND token = 'MKeTUB8/uVvgpWVAwkjl8cnGfFifOhsMWK3dJdTDryQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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