SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7bac0ec0e03238f017a6aff08fc79d3f8613cf51077ddae6a7c90dd9008305b2' 
  AND token = 'd3tM8kVNMYVQoUProvrH4mxxylXnhOSHFPtGjKlvu3k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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