SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8c3887ee244dad66a0e71c0e6ca713bb12999797c8aa39badcf24b679480d44' 
  AND token = 'UqTUmfAAij86JkCpjDJnjSnWvKxHT28I3B3k9oGIEs8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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