SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '281b0b8084abbe05e247698486b2f1ecde8f43899f5d9a2ff6fed6d778a39aa3' 
  AND token = 'lO0/YyPYbXULsxKZ2K4gvRtj60j9z9+Iz5XbKGIOTUE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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