SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b5ca3bcb7864ab389214c07afc1664ff020bf30ee7d79ae066cfc4fc5856da1' 
  AND token = 'My0fHvKxH7sbQppnPDCqz6BXeACczNai7Kzuu34FQdE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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