SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b53680e8f91dfd37e307450cb28ebee776c741d7c0176c25d9060b938f531061' 
  AND token = 'cusryIY4EiZQDlCZVpa0656mQl5JYA+1PWtWurhQZyA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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