SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18603879d3fda5d2d1851f2b59388831beecb84ac052a7c8c45522553b238562' 
  AND token = 'aoXF5TMyUYw34/p3gPC/afUxh8AHJ/hv7SXONohGe8c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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