SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b53e65a39d3553beff21d42df73bf93f4bc66250f3818b1f29502decdc3667f7' 
  AND token = 'FJNcuVvW3hA8wgrXJZtMynuSKorujPB3ZkxHTF9/ooI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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