SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '13a4e540c0002af6c60b029e20dbd992aff3e887c259ac2af36dca895427f127' 
  AND token = 'TMnOYID4yG6QNgsg3C/aHoy8KVpqqqBI3uMciecsNUk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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