SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4099ef2808250652c8d45afa5606542fda659a266ff3ac515c70f98539fc54e' 
  AND token = 'Djk5gSvW+HJovBGAx0gMWcmIHge/9sU5Z94npESy+hc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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