SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c52ddc2dc01b8dd3f87036c7acd522551bee783f3744e7b5b9548f869bdfb859' 
  AND token = 'scNYD02zgCNKzYp+1hh/Wl/hvSYXwdTUJlYDR9cy4uc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}