SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f208a384a9609f376f7e7dda8340a8f099fbbd0d3c2d4702a893449f53ada139' 
  AND token = 'wUIUoFl7KrlTBWuNNYqmrifKyMJVGNNGWe6+MF6QDTw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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