SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8816ed90eac6f76ac389519332fce591f48e07838f029fb9bb1b094bc39a2ed' 
  AND token = 'jImkz4wxyN1gxicMAwwxhZYxq/NH+3hqKM4J1v2C0IA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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