SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4614988290f657ba8ad961411e1fcdc652efa05ff1cecc930d041dc891d973e4' 
  AND token = '8IVxYJRi+a1X/USqZebCEiXEKIscgNGgsBCOClDKQeg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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