SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b1250049316724069e4fc477e7ac86940ebe1c743be4026ef2489e5e208ce2a' 
  AND token = 'ZfJZZe+6TwYPro/peBDGEp6mL5l+QcdGcFfo9OeQLkM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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