SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6fccf925ec15a14ef771bcbebe842d8f0c63976efb0eb4a89cc067a8557a399' 
  AND token = 'qwXrClnXFHO3fye3ALMfHOKhg1qbtIFZu4q4mgrgx5Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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