SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '30bd5d9a3d0d2425f8adda624b462c48e38f6a2143528d9f36fcb1eb75e10ca1' 
  AND token = 'wc3cKpqYVSCc3zzbm7MqVk/wtQ0qSYCcPsyvnu2dXgI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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